Miners accomplished the tunnel hole-through on August 12. “This is an historic moment,” said site manager Dr. Willi Kleine during the ceremony attended by 100 guests. “The Clara tunnel, named after the wife of Supervisory Board President Dr. Peter-Alexander Wacker, is vital for our mine’s future and plays a major long-term role in securing jobs in Stetten.”
The new 900-meter tunnel eases burdens on the current tunnel, used to transport material, equipment and people until now. Due to space limitations and safety, only small, four-wheel specialty vehicles can pass through the current tunnel. Larger mining-specialized machines, such as wheel loaders and dump trucks, are usually too big and must be disassembled into their component parts prior to transport. With a 36 m2 cross-section and a 10% maximum incline, the new access route is suitable for large road vehicles. “This allows us to run the salt mine far more efficiently in terms of logistics and to directly transport backfill into the salt mine by truck,” said Kleine.
During the 14-month construction period, 50,000 m3 of rock were removed. Most of the material was reused for construction of roads and forest paths in the immediate vicinity. Originally planned for June, the hole-through was delayed due to geological conditions that turned out to be far more difficult than expected, particularly in water-transporting layers. Mine reinforcing work included the use of novel polymer binders from the WACKER POLYMERS division.
Overall, mine director Alfred Höllerbauer was very satisfied with the construction work. “Despite some challenging conditions, we did not have a single accident during construction.” Höllerbauer expects the tunnel to open by the second half of October at the latest. “The next stage involves pouring concrete for the road surface and finishing the tunnel mouth. When this work has been completed, the first trucks can begin their runs.”
The Stetten Salt Mine
The Stetten salt mine is one of the oldest of its kind in Germany. In 1852, the “Stetten Saltworks” (near Haigerloch, southwest Germany) was built at the suggestion of Prussian King Frederick William IV. The mining of rock salt began in 1858, initially for table and animal-feed salt. Following World War I, the mine became the property of “Preussischen Bergwerks und Hütten AG,” today’s TUI tour operator. WACKER leased the mine in 1924 to cover its rising rock salt needs, and purchased it in 1960.
Today, the Stetten salt mine produces about 500,000 metric tons of rock salt annually for industrial and de-icing purposes. A large portion of the rock salt is shipped to WACKER’s Burghausen plant, where it is used in the manufacture of silicones, hyperpure silicon, organic intermediates and pyrogenic silica.